Tractors typically have a rear mounted, rear facing power take-off shaft that is driven by the engine of the tractor through a clutch. The shaft is typically splined in order to facilitate coupling PTO-driven implements to the tractor.
There is a need, especially with small tractors that have a limited hydraulic pump, for an auxiliary system that will provide sufficient hydraulic pressure and flow to drive hydraulically powered implements, such as, for example, a snow blower, a broom, or a loader. In the past, PTO driven auxiliary hydraulic systems are known. Usually such systems are coupled to the PTO output shaft with a hydraulic pump being driven by the PTO shaft. Such systems principally have been stand-alone systems that include a closed loop hydraulic system incorporating both a filter and a radiator for filtering and cooling the hydraulic fluid in the auxiliary system. Such systems are both bulky and expensive to manufacture because of the numerous components involved.
In at least one case, Vachon, U.S. Pat. No. 5,332,053 issued Jul. 26, 1994, the auxiliary hydraulic system is plumbed into the hydraulic system of the tractor itself and still includes a PTO driven hydraulic motor (utilized as a pump). Vachon at least implies and the hydraulic connections indicate that full hydraulic pump flow to the auxiliary hydraulic system is provided. Such flow takes pressure at a point where it could exceed 2,500 psi. Such pressure would likely blow the shaft seal out of the motor/pump. Hydraulic flow of such a device would likely be on the order of 20 gallons per minute.
There is a need then for a PTO driven hydraulic system that is both cooled and filtered by the hydraulic system of the tractor on which the PTO driven hydraulic system is mounted. Additionally, it is very desirable to minimize both the flow rate of the hydraulic fluid tapped from the tractor hydraulic system and the pressure of such fluid, thereby leaving the greatest portion of hydraulic capacity generated internally by the tractor to other tasks.